CT scanner inventor Robert Ledley dies

Robert S. Ledley, a Georgetown University physicist who was credited with inventing the first full-body CT scanner, a machine that revolutionized medical diagnostics by allowing doctors to gaze inside their patients' tissues without ever touching a scalpel, died Tuesday at the Arden Courts nursing facility in Kensington, Md. He was 86.

His death, of Alzheimer's disease, was confirmed by his son, Fred Ledley. Robert Ledley was a Laurel, Md., resident.

Ledley was trained as a dentist -- in case his career in physics didn't pan out -- and became a scientific polymath. In the late 1950s, when most doctors still worked with pen and paper, he became a prominent advocate for using data processors to help diagnose disease.

In 1973, Ledley introduced one of the most powerful diagnostic aides since the discovery of X-rays in 1895. He called his invention the automatic computerized transverse axial scanner, or ACTA. It was, in effect, the first machine capable of producing cross-sectional images of any part of the body.

Today, the CT scan is a commonplace medical procedure. Ledley's prototype did not include the modern machine's dreaded tunnel -- in his original design, the patient passed through a thinner ringlike scanner -- but most CT scanners today rely on his basic concept.